Stepped-up security screenings produced long lines for travelers at Brazil's main airports on Monday in the aftermath of the truck attack in Nice, France and weeks ahead of the Olympic Games in the South American nation.
Scores of passengers lost domestic flights after authorities began patting down travelers and checking their luggage after passing through metal detectors, screening previously required only for international flights.
Authorities insisted the new screenings were not related to attacks abroad, but were in line with international security standards.
Brazilian officials, reviewing preparations for the Games after the Nice massacre, stepped up security cordons, added roadblocks and planned to frisk more visitors in Rio de Janeiro for the August 5 Olympic Games. The attack killed 84 people and injured 85 others, including 18 critically.
Local authorities expect more than 500,000 foreign tourists to land in the coastal city of Rio de Janeiro for the Olympics.
Angry passengers waited for hours in long lines at the Santos Dumont airport in Rio de Janeiro. About 50 passengers missed their morning flights at Sao Paulo's Congonhas airport, a local airline employee told Reuters.
Despite the long lines, few flights were delayed or canceled, according to Brazil's state-run airport operator Infraero.
Brazilian customs workers last week started an indefinite strike to demand higher wages, slowing down the inspection of luggage and imports arriving at airports and other entry points.
A crippling political and economic crisis as well as the spread of the mosquito-borne Zika virus have raised questions about Brazil's ability to successfully host the global sporting event for the first time ever in South America.